Leonard Hayflick
Leonard Hayflick
Birth: 20 May 1928
Philadelphia, Pennsylvania
Age: 92 years, 246 days
Country: United StatesUSA

Leonard Hayflick (born 20 May 1928) is an American anatomist, best known for discovering that human cells divide for a limited number of times in vitro[1] (refuting the contention by Alexis Carrel that normal body cells are immortal). This is known as the Hayflick limit. He is a past president of The Gerontological Society of America and was a founding member of the council of the National Institute on Aging (NIA).

Hayflick is the author of the book, “How and Why We Age”, published in August 1994 and available in 1996 as a paperback.[2] This book has been translated into nine languages.

Hayflick and his associates have vehemently condemned "anti-aging medicine" and criticized organizations such as the American Academy of Anti-Aging Medicine.[3] Hayflick has written numerous articles criticizing both the feasibility and desirability of human life extension,[4][5] which have provoked responses critical of his views.[6]


Leonard Hayflick was born 20 May 1928 in Philadelphia, Pennsylvania. He received his Ph.D. at the University of Pennsylvania in 1956. After receiving a post-doctoral Fellowship for study at the University of Texas Medical Branch in Galveston, he returned to Philadelphia, where he spent ten years as an Associate Member of the Wistar Institute and two years as an Assistant Professor of Research Medicine at the University of Pennsylvania.

In 1968 Hayflick was appointed Professor of Medical Microbiology at the Stanford University School of Medicine, Stanford, California. Hayflick resigned from Stanford in 1976 while he was the subject of an inquiry by Stanford into his professional conduct, an episode that he characterized as "Gestapo-like" and that was later condemned by 85 prominent biologists who viewed him as having been "exonerated" by subsequent events.[7] In 1982 he moved to the University of Florida, Gainesville, where he became Director of the Center for Gerontological Studies and Professor of Zoology in the College of Liberal Arts and Sciences and Professor of Microbiology and Immunology in the College of Medicine. He then joined the faculty of the University of California in 1988, where he is currently Professor of Anatomy.

He is a member of twenty scientific and professional societies in which he has held several high offices including President of The Gerontological Society of America from 1982 to 1983. He was a founding member of the Council of the National Institute on Aging and Chairman of its Executive Committee. He was a consultant to the National Cancer Institute and the World Health Organization, and is now a member of several scientific advisory boards. He was Chairman of the Scientific Review Board of the American Federation for Aging Research where he was also a vice president and a Member of the Board of Directors. He was Editor-in-Chief of the international journal Experimental Gerontology for 13 years.

Hayflick is the recipient of more than twenty-five major awards including the $20,000 Brookdale Award and the Kleemeier Award from the Gerontological Society of America and the Sandoz Prize from the International Association of Gerontology.

Hayflick is also one of several prominent biologists featured in the 1995 science documentary Death by Design/The Life and Times of Life and Times.

Research details

Hayflick Limit

Hayflick is known for his research in cell biology, virus vaccine development, and mycoplasmology. In 1962 he discovered that, contrary to the belief prevalent at the turn of the century, cultured normal human and animal cells have a limited capacity for replication. This discovery, known as the Hayflick limit, overturned a dogma that existed since Alexis Carrel's work early in this century that claimed that normal cells would proliferate continuously in culture. Hayflick's results focused attention on the finite cellular life-span was the fundamental location of age changes and that immortality was a key feature of tumor cells. Hayflick demonstrated for the first time that mortal (normal) and immortal (malignant) mammalian cells existed.

Other Work

Hayflick developed the first normal human diploid cell strains for studies on human aging and for research use throughout the world, and produced the first oral polio vaccine made on a continuously propagated cell strain.

Hayflick is also known for his discovery of the cause of primary atypical pneumonia (“walking pneumonia”) in humans. The etiological agent was first thought to be a virus, but Hayflick showed that it was, in fact, a mycoplasma] a member of the smallest free-living class of microorganisms. The etiological agent was named by him as Mycoplasma pneumoniae, and was first grown by Hayflick on a medium he developed and that bears his name. It is now used worldwide for mycoplasma isolation and research.

Hayflick is the author of over 275 scientific papers, book chapters and edited books of which four papers are among the 100 most cited scientific papers of the two million papers published in the basic biomedical sciences from 1961 to 1978.


  1. Hayflick L (1965). "The limited in vitro lifetime of human diploid cell strains". Experimental Cell Research 37 (3): 614–636. doi:10.1016/0014-4827(65)90211-9. PMID 14315085.
  2. Hayflick, Leonard (January 23, 1996). How and Why We Age (Reprint ed.). Ballantine Books. ISBN 0-345-40155-7.
  3. Olshansky SJ, Hayflick L, Carnes BA (2002). "Position statement on human aging". The Journals of Gerontology, Series A 57 (8): B292–B297. doi:10.1093/gerona/57.8.B292. PMID 12145354.}
  4. Hayflick L (1998). "Aging is not a disease". Aging 10 (2): 146. PMID 9666198.
  5. Hayflick L (2004). "'Anti-aging' is an oxymoron". The Journals of Gerontology, Series A 59 (6): B573–B578. doi:10.1093/gerona/59.6.b573. PMID 15215267.
  6. Rae, MJ (2005). "Anti-aging medicine: fallacies, realities, imperatives". The Journals of Gerontology, Series A 60 (10): 1223–1227. doi:10.1093/gerona/60.10.1223. PMID 16282551
  7. Philip M. Boffey, "The Rise and Fall of Leonard Hayflick," New York Times (January 19, 1982)
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